Field of the Invention
Gaskets having an edge coating on at least one vertical edge (lying between the two faces of the gasket) of the gasket is provided. The edge coating provides a much greater sealing ability to soft gasket material. The present invention offers gasket edge coatings which are optimized and thus improved. Edge coatings can be put on gaskets to intentionally obtain a total seal against fluids.
The sealing ability of soft gasket materials is extremely important, and has been the focus of considerable development effort. The edge coating is one feature which has recently been developed to provide a greater sealing ability to the gasket. Advantageously, the edge coating allows the remainder of the gasket to optionally and preferably have no coating. When the gasket is uncoated, or has only a release coating, the compression failure resistance of the gasket is preserved.
Many features have been used with gaskets in order to provide good or better sealing ability, particularly against fluids.
Beading on the face of the gasket is known. Such beading is a raised area put on the face. Beading, however, does not extend past the edge, and does not extend onto the edge. Although the beading is used to enhance sealing ability, the beading fails to consistently provide a perfect seal.
One gasket material which is offered to provide a good seal at high temperatures is described in U.S. Pat. No. 5,240,766. This reference describes a soft gasket sheet material having fiber, filler and binder. According to the reference, the filler component provides a desirable sealability.
Another reference which describes gasket sheet materials that provides good sealing properties is U.S. Pat. No. 5,437,767. This reference describes a gasket sheet material with fiber and filler. The filler component must include a gel-forming mineral. This filler gives the gasket good sealing properties, especially against polar liquids.
Yet another type of gasket reference relies on coatings to provide or enhance the sealing ability of the gasket. For example, U.S. Pat. No. 4,499,135 impregnates the gasket with a silicone resin to improve resistance to water/antifreeze mixtures; U.S. Pat. No. 3,661,401 requires that the gasketing is given a coating which covers the entire gasket, vertical edges included; and U.S. Pat. No. 4,600,201 impregnates the gasket mat with a polymerizable liquid impregnating agent and applying to at least one part of at least one mat face, a coating containing a polymerizable polymer material. Gasketing which is completely coated, however, in general will perform poorly at higher pressures, which severely limits the field of use of the gaskets.
It has been discovered that by edge-coating the vertical edges of gaskets, especially the vertical edges around an aperture, and optionally the outer edge of the gasket, the resulting gasket will give a good and even a total seal against fluids. The present invention, however, describes how these edge coatings can be optimized to provide better sealing ability and to more consistently provide total seals.
Accordingly, it is an object of the present invention to describe an optimized edge coating for the vertical edges of a soft gasket material.